The Zildjian SL21R Sound Lab Project 391 21 Inch Limited Edition Ride Cymbal that is made of B15 Alloy (85% copper, 15% tin). This combination of metals produces a unique and consistent sound that cuts through any mix. Not only is this made of B15 alloy but the other unique aspect of this cymbal is the two step lathing process imparts a unique surface finish that is not only visually stunning but is pleasing to the ears. This is a medium cymbal in a natural brilliant finish.